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Varicella & Pregnancy

Treatment in pregnancy:

Chicken Pox Infection
  • Immunized or Hx of past infection:
    • exposure: nothing to do.
    • simple rash: acyclovir 800mg PO 5x/day for 7 days
    • severe infection or pneumonia, admit for IV acyclovir and supportive care.
  • Not Immunized:
    • exposure: consider VZIG, give first dose within 96 hours if possible, and up to 10 days from exposure.
    • simple rash: acyclovir 800mg PO 5x/day for 7 days
    • severe infection or pneumonia, admit for IV acyclovir and supportive care.
Zoster (Shingles)
  • acyclovir 800mg PO 5x/day for 7 days 
  • No role for VZIG if patient is immunized or has Hx of prior infection.
  • VariZIG not proven to help once infection occurs, only in reducing chance of developing infection.
  • Women should be immunized as soon as possible, preferably 1 month prior to becoming pregnant, or as soon as possible after delivery.
  • VariZIG is given to pregnant non-immunized women who are exposed (legit exposure) with plans for vaccination after delivery.
  • Acyclovir is given to anyone who is vaccinated and shows symptoms.


  • Chickenpox is caused by the varicella-zoster virus, a member of the herpes family of viruses.
  • Most people are exposed or immunized as children.
  • Infection is less severe in children than adults and usually has less morbidity.
  • The vaccine was introduced in 1995.
  • Acute infections causes a rash of the fact-trunk- and extremities that causes macule-papule-then vesicles then crusting. Lesions appear over 4 days, crust by day 6 and slough off within a week or two.
  • Prodrome includes fever, malaise, and myalgia one to four days prior to the onset of rash.
  • Vaccination protects 98-99% of people after 2 doses.
  • Those with varicella can pass it along more easily than those with zoster.
  • People are infectious from 1-2 days prior to symptoms until all lesions have crusted over.
  • Passage also occurs from exposure to secretions from mucus membranes in varicella, more so than with exposure to fluid in vesicles.
  • Incubation is 10-21 days post exposure.


<2% of infections occur in adults >20 yo, about 25% of mortality is in this age group.  1 to 5 cases per 10,000 is the estimated incidence, but it isn’t reportable so exact numbers are unknown.


Complications are more common in adults than children and include
  • meningitis, encephalitis, cerebellar ataxia, pneumonia, glomerulonephritis, myocarditis, ocular disease, adrenal insufficiency, and death.
  • Secondary bacterial infections can also occur in patients with significant cutaneous disease.
  • Maternal varicella during pregnancy is associated with the development of herpes zoster during infancy.
  • Varicella infection  immediately before or after delivery puts the baby at risk for neonatal varicella, which varies from mild rash to disseminated infection.
  • Maternal zoster is generally not associated with fetal or newborn disease.
  • Most common complication of varicella in pregnancy is pneumonia.
    • There is an increased rate with varicella in pregnancy but the numbers have improved with antiviral therapy. It was reported as up to 20% experiencing pneumonia, but may be as low as 2.5% of cases now. Smoking and having >100 vesicles increases the risk.
    • The pneumonia usually develops within one week of the rash
    • The clinical course is unpredictable and may rapidly progress to hypoxia and respiratory failure.
    • CXR findings include a diffuse or miliary/nodular infiltrative pattern
  • Congenital Varicella Syndrome occurs in less than 2% of pregnancies where mom has primary varicella in the first 20 weeks.
  • It is more rare after 20 weeks gestation.
  • Only one published case report of this occurring due to zoster since 1987
  • Congenital varicella syndrome includes limb hypoplasia, skin lesions, neurologic abnormalities, and structural eye damage.
  • Mortality rate of 30 percent in the first few months of life.
  • 15 percent risk of developing herpes zoster by age 4.


  1. Cytomegalovirus, parvovirus B19, varicella zoster, and toxoplasmosis in pregnancy. Practice Bulletin No. 151. American College of Obstetricians and Gynecologists. Obstet Gynecol 2015;125:1510–25.
  2. CDC, Prevention of Varicella: Recommendations of the Advisory Committee on Immunization Practices (ACIP)  Direct Link
  3. Royal College of Obstetricians and Gynecologists, Chicken Pox In Pregnancy, Green-top Guideline No. 13, January 2015  Direct Download
  4. Enders G, Miller E, Cradock-watson J, Bolley I, Ridehalgh M. Consequences of varicella and herpes zoster in pregnancy: prospective study of 1739 cases. Lancet. 1994;343(8912):1548-51. PubMed
  5. Stone KM, Reiff-eldridge R, White AD, et al. Pregnancy outcomes following systemic prenatal acyclovir exposure: Conclusions from the international acyclovir pregnancy registry, 1984-1999. Birth Defects Res Part A Clin Mol Teratol. 2004;70(4):201-7.PubMed
  6. Cohen A, Moschopoulos P, Stiehm RE, Koren G. Congenital varicella syndrome: the evidence for secondary prevention with varicella-zoster immune globulin. CMAJ : Canadian Medical Association Journal. 2011;183(2):204-208. doi:10.1503/cmaj.100615. PubMed

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